1. Field of the Invention
The present invention relates to a record medium onto and from which record information is optically recorded/reproduced, a record medium manufacturing apparatus for manufacturing the record medium, and an information recording/reproducing apparatus for record/reproducing the record information onto and from the record medium. More particularly, the present invention relates to a record medium on which so-called a groove track and a land track are both formed as the track for recording the record information, a record medium manufacturing apparatus for recording the record medium, and an information recording/reproducing apparatus for record/reproducing the record information onto and from the record medium.
2. Description of the Related Art
In order to improve a record density of an optical disc, research and development with regard to a so-called xe2x80x9cland/groove recordxe2x80x9d are carried out for forming an information mark corresponding to each record information on both of a groove track of the optical disc (i.e., a convex track when observed from a surface of a side, to which a light beam is irradiated, of the optical disc) and a land track (i.e., a concave track when observed from the surface of the side, to which the light beam is irradiated, of the optical disc) formed adjacent to the groove track, and then recording the record information onto both of the groove track and the land track.
Here, as an optical disc employing the land/groove record, there is a so-called DVD-RAM (DVD-Random Access Memory) standardized in recent years. As a method of judging whether the light beam is being irradiated onto the groove track or the land track when the record information is recorded and reproduced onto and from this DVD-RAM, there is a first method of detecting a pre-pit (which is formed so as to be deviated toward an outside or an inside in a radius direction from a central line in the groove track or the land track) formed within a CAPA (Complimentary Allocated Pit Address) area formed on the information record surface of the DVD-RAM, and thereby judging whether the light beam is being irradiated onto the groove track or the land track.
In addition, the above-mentioned standard of DVD-RAM is described in detail in, for example, NIKKEI Electronics, Oct. 10, 1997 (No. 700), pages 307-319, and NIKKEI Electronics, Oct. 20, 1997 (No. 701), pages 167-186.
Moreover, the reason why it is judged whether the light beam is irradiated onto the groove track or the land track when the record information is recorded and reproduced onto and from the DVD-RAM is that, since a polarity of a so-called tracking error signal is inverted depending on whether the light beam is irradiated onto the groove track or the land track, a tracking servo control can not be accurately carried out unless it is judged. The reason why this inverting phenomenon is induced is as follows. That is, if the light beam is irradiated onto the groove track, the light beam is irradiated to the convex portion to thereby decrease a light quantity of a reflection light thereof. Thus, when the light beam is accurately irradiated onto the groove track, the light quantity of the reflection light thereof is smaller than that of the case when the tracking is deviated. On the contrary, if the light beam is irradiated onto the land track, the light beam is irradiated onto the concave portion having a mirror surface to thereby increase a light quantity of a reflection light thereof. Thus, when the light beam is accurately irradiated onto the land track, the light quantity of the reflection light thereof is larger than that of the case when the tracking is deviated.
On the other hand, there is a second method of judging, whether the light beam is irradiated onto the groove track or the land track, by using a difference between quantities of reflection lights of the light beams resulting from a difference between widths of a groove track and a land track, for example, as disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 9-120584).
However, according to the first method, by the existence of the CAPA area, the groove track or the land track does not exist in that portion. This results in a problem that this record format is not suitable for an operation of recording/reproducing the record information, in which a continuity is important, such as video information and audio information.
Moreover, in case of the record format of the DVD-RAM in which the groove track or the land track is intermittent, there is such a problem that the record information recorded on the DVD-RAM cannot be reproduced by using a reproducing apparatus for reproducing, for example, DVD-ROM (DVD-Read Only Memory) in which the groove track or the land track is formed without the intermittence (recently, this kind of reproducing apparatus begins to be commercially sold)
On the other hand, the second method has a problem that, when the groove track and the land track are formed at the same width, it is impossible to discriminate between the types of the tracks to which the light beam is irradiated.
The present invention is proposed in view of the above mentioned problems. It is therefore an object of the present invention to provide a record medium, on which record information is recorded on both of a groove track and a land track which allows to record and/or reproduce the record information while maintaining a continuity of the record information and with accurately judging the types of the tracks onto which a light beam is irradiated, a record medium manufacturing apparatus for manufacturing the record information, and an information recording/reproducing apparatus for record/reproducing the record information onto and from the record medium.
The above object of the present invention can be achieved by a record medium such as an optical disc etc., provided with: a main body; a groove track formed on the main body, as one track for recording information onto which a light beam for recording and/or reproducing the information is irradiated; and a land track formed on the main body, which is adjacent to the groove track, as another track for recording the information onto which the light beam for recording and/or reproducing the information is irradiated, wherein a judgment wobble, which has a judgment pattern to judge whether the light beam is irradiated onto the groove track or the land track, is formed on only one side wall of the groove track.
According to the record medium of the present invention, since the judgment wobble is formed on only one side wall of the groove track, a wave form of a light detection signal detected at the judgment wobble when the light beam is irradiated onto the groove track is different from that when the light beam is irradiated onto the land track. Accordingly, when recording/reproducing the information, it is possible to precisely judge whether the light beam is moving on the groove track or the land track. Consequently, it is possible to record/reproduce the information while accurately controlling the irradiation condition of the light beam.
Further, since the judgment wobble is formed such that the groove track or the land track is not intermittent by the existence of the judgment wobble, it is possible to record/reproduce the information continuously, which is very preferable when recording/reproducing video information, audio information and the like for which the continuity of the information is important.
In one aspect of the record medium of the present invention, a wobble having another pattern different from the judgment pattern is formed in an area of the only one side wall other than an area where the judgment wobble is formed.
According to this aspect, the periodic signal used to move the record medium for example, can be recorded as the wobble on the only one side wall of the groove track which wobbles at a period or cycle corresponding to the periodic signal, without reducing the record capacity of the groove track or the land track.
In this aspect, the another pattern may correspond to address information indicative of a record position on the record medium.
By constructing in this manner, the address information can be recorded and the judgment wobble can be formed without reducing the record capacity of the groove track or the land track.
In another aspect of the record medium of the present invention, the main body is shaped in a disc, and the groove track and the land track are formed such that the information is recorded and/or reproduced while the light beam is relatively moving on the groove track and the land track alternately for each rotation of the record medium.
According to this aspect, it is possible to continuously record/reproduce the information at a high density.
In this aspect, the judgment wobble may be formed adjacent to a boundary between the land track and the groove track in a circumference direction of the record medium.
By constructing in this manner, it is possible to judge whether the light beam is irradiated onto the groove track or the land track immediately after the groove track and the land track are exchanged.
In another aspect of the record medium of the present invention, no wobble is formed in an area of the only one side wall other than an area where the judgment wobble is formed.
According to this aspect, the judgment wobble can have any judgment pattern as long as it can be recognized as the judgment pattern. Thus, it is possible to simplify the judgment pattern, so that the formation of the judgment wobble can be also rather easy in the manufacturing process.
The above object of the present invention can be also achieved by a record medium manufacturing apparatus for manufacturing the above described record medium of the present invention. The record medium manufacturing apparatus is provided with: a track forming device such as an optical head etc., for forming the groove track and the land track on the main body; a generation device such as a mark signal generation circuit etc., for generating a wobbling signal corresponding to the judgment pattern; and a wobble forming device such as an optical head etc., for forming the judgment wobble on the only one side wall, on the basis of the wobble signal generated by the generation device.
According to the record medium manufacturing apparatus of the present invention, since the judgment wobble is formed on only one side wall of the groove track, a wave form of a light detection signal detected at the judgment wobble when the light beam is irradiated onto the groove track is different from that when the light beam is irradiated onto the land track. Accordingly, when recording/reproducing the information, it is possible to precisely judge whether the light beam is moving on the groove track or the land track. Consequently, it is possible to record/reproduce the information while accurately controlling the irradiation condition of the light beam.
Further, since the judgment wobble is formed such that the groove track or the land track is not intermittent by the existence of the judgment wobble, it is possible to record/reproduce the information continuously.
In one aspect of the record medium manufacturing apparatus of the present invention, the main body is shaped in a disc, and the track forming device forms the groove track and the land track such that the information is recorded and/or reproduced while the light beam is relatively moving on the groove track and the land track alternately for each rotation of the record medium.
According to this aspect, it is possible to continuously record/reproduce the information at a high density.
The above object of the present invention can be achieved by an information recording/reproducing apparatus for recording/reproducing information with respect to the above described record medium of the present invention. The information recording/reproducing apparatus is provided with: a detection device such as an optical pickup etc., for detecting the judgment wobble; a judgment device such as an LG (Land/Groove) judgment section etc., for judging whether the light beam is moving on the groove track or the land track on the basis of the judgment wobble detected by the detection device; and a recording/reproducing device such as an optical pickup etc., for recording/reproducing the information with respect to the groove track and the land track, on the basis of a judgment result of the judgement device.
According to the information recording/reproducing apparatus, since the information is recorded and/or reproduced while judging whether the track onto which the light beam is irradiated is the groove track or the land track, it is possible to record and/or reproduce the information precisely and certainly.
In one aspect of the information recording/reproducing apparatus of the present invention, the main body is shaped in a disc, and the apparatus further comprises: a tracking servo device such as an optical pickup etc., for servo-controlling an irradiated position of the light beam on the record medium in a radial direction of the record medium; and a tracking control device such as a tracking controller etc., for controlling the tracking servo device on the basis of the judgment result.
According to this aspect, since the tracking servo is performed while judging whether the track onto which the light beam is irradiated is the groove track or the land track, it is possible to record and/or reproduce the information precisely while precisely controlling the irradiated position of the light beam in the radial direction of the record medium.
The nature, utility, and further features of this invention will be more clearly apparent from the following detailed description with respect to preferred embodiments of the invention when read in conjunction with the accompanying drawings briefly described below.